The Immunology of the Gastrointestinal System

Distinctive features of the gastrointestinal immune system include its size, organisation and perpetual exposure to dietary antigens and a large and complex population of resident microorganisms. The mucosal immune system maintains homeostasis by avoiding tissue damaging responses to the luminal contents, whilst at the same time retaining the capacity to provide protection against pathogens. The luminal environment changes markedly from the proximal to the distal gastrointestinal tract, which may explain the restriction of many immune-mediated diseases to specific regions. Diseases that are considered in this chapter include pernicious anaemia, coeliac disease, those related to immunodeficiency, inflammatory bowel disease and bacterial infections that affect distinct regions of the gastrointestinal tract.